utils.sh: fixed function_exists not to display grep result

lib/utils.sh

@@ -26,8 +26,11 @@ function_exists() {
         die 11 --force
     fi
 
-    LC_ALL=C type -t $1 | grep function
+    if [[ $(LC_ALL=C type -t $1 | grep function) ]]; then
-    return $?
+        return 0
+    else
+        return 1
+    fi
 }
 export -f function_exists